This invention relates to a wheel cylinder containing an auto-adjuster for a drum brake.
An auto-adjuster of the type disclosed by U.S. Pat. No. 3,712,425, is intended for use in a two leading shoe brake. The auto-adjuster of this type is operated in a space exposed to the air, and the adjusting operation may become unstable because of mud, or foreign particles and the like adversely affecting the component parts thereof.
The prior art further includes a structure disclosed by U.S. Pat. No. 4,503,424 in which an auto-adjuster is contained in a wheel cylinder for a two leading shoe brake. In this auto-adjuster, however, the quantity of the adjustment of the gap between shoes is determined only by the pitch of a multiple thread. Since this adjustment is of a one-shot type in which the adjustment is completed within one round of brake operation, the quantity of the adjustment tends to be affected by the heat distortion of a brake drum. Moreover, the piston in this device is unduly complicated to construct.